Abstract

In coating C-glass fibres, a coating material (I) like SiO2 is used, which has cationic character and a high acidity. - (I) is a cationic SiO2 sol with pH 2.5-5.5, pref. 3.5-4.5. Treatment with Al hydroxychloride is used to provide the cations and adjust the pH. Alternatively, the pH is adjusted to the required range by adding acid or alkali, pref. acetic acid. The (I) soln. contains 0.1-5.0, pref. 0.5-1.5 (wt.)% solids.